The invention relates to a network element with at least one first input, to which an optical signal may be supplied, and at least one first output, which is designed to emit an optical signal.
US 2009/0175620 A1 discloses a network element of the type stated in the introduction. This known network element has a first input, to which an optical signal may be supplied. The optical signal comprises a plurality of different channels with in each case one dedicated frequency or wavelength. Furthermore, the known network element comprises an optical switch, which applies individual channels of the optical input signal to predeterminable outputs by means of optical filters. In addition, a further input may be provided, being adapted to add an additional signal to the output signal. The network element may therefore be used for converting predeterminable channels of the optical input signal, unchanged, into the output signal and extracting individual channels of the optical signal and providing said individual channels at a further electrical or optical output. Finally, the network element may receive an input signal via a further input which is likewise supplied to the output signal.
However, this known device has the disadvantage that, owing to the use of the optical switch, high insertion losses occur. In some embodiments, the filters used in the optical switch may cause phase ripple, which has a disadvantageous influence on the signal quality and restricts the possibility of cascading a plurality of said network elements. If the capacity of an optical network equipped with the known network element is intended to be increased by virtue of a greater number of optical channels with in each case a dedicated, associated wavelength, at least some of the optical switches need to be replaced. Therefore, the increase in the capacity of the optical network involves considerable complexity which means longer downtimes of the optical network. Furthermore, the known network elements cannot be scaled during operation, i.e. it is not possible to increase or lower the number of channels after installation.
It is therefore an object of the present invention to provide a network element having fewer insertion losses, having less influence on the signal quality and allowing easy scalability of the optical network equipped with the network element.